<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>

    </title>
    <style>
        .parent{
            
            border: 1px solid rebeccapurple;
        }
        .clear{
            clear: both;
        }
        .c1{
            float: right;
            width: 100px;
            height: 500px;
            background-color: rgb(35, 64, 143);

        }
        .c2{
            float: left;
            width: 100px;
            height: 400px;
            background-color: rgb(12, 233, 67);
        }
        .parent::after{
            content: '';
            display: block;
            clear: both;
        }
    </style>
</head>
<body>
    <div class="parent">
        <div class="c1"></div>
        <div class="c2"></div>
        <!-- <div class="clear"></div> -->

    </div>
</body>
</html>